The present invention concerns a method for starting a burner device for a gas turbine, wherein the burner device comprises at least one burner member, arranged to be supplied with a liquid fuel, and an ignition member, which is activated for igniting a fuel which is supplied to the burner member.
Such starting methods are already well known. In the prior technology, the ignition member, which preferably is formed by a separate ignition burner, is often activated by means of an ignition plug or the like, such that an ignition flame is obtained. The ignition burner uses for example liquefied petroleum gas or natural gas as fuel.
Since the invention is particularly suitable in connection with burner devices which use a liquid fuel, preferably an oil, it will below in an exemplifying but not limiting purpose be described with reference to such a burner device.
In a burner device of this kind, the main portion of the air which is supplied to a combustion chamber connected to the burner device is supplied via the flame zone which is defined by the burner member or members included in the burner device.
During the start of the burner device it is important that the concentration of fuel in an ignition zone of the burner member is such that the activation of the ignition member immediately results in a corresponding ignition of the fuel and in the generation of a burner member flame. If the fuel concentration is such that no immediate ignition and generation of a burner member flame is obtained, the mixture of fuel and incoming air will flow through the combustion chamber and into a subsequent turbine. If the ignition of the fuel takes place at such a late stage, the generated flame will extend all the way through the combustion chamber and into the turbine as far as the mixture of fuel and air which may be ignited extends. Said mixture may extend all the way to and into an exhaust channel connected to the turbine. When the exhaust channel in this manner is filled with an explosive mixture which may ignited, this may lead to the fact that an explosion takes place in the exhaust channel. Such an explosion may have devastating consequences and should therefore be avoided as far as possible.
Starting methods according to prior technology are thus very sensitive and require a very precise control of the fuel concentration in the ignition zone of the burner member or members at the moment when the fuel is supplied to said zone and the ignition of the same shall be carried out for generating a burner member flame.